Dynamo-electric machine.



No. 842,963. PATENTED FEB. 5, 1907.

M. G. A, LATOUR.

DYNAMO ELECTRIC MACHINE.

APPLICATION FILED NOV. 9, 1905.

FY92, n n A i .1 a i Witnesses: inventor: aM/l/flza/wzfif i jMarius CJLLacour.

UNITED STATES PATENT OFFICE.

MARIUS C. A. LATOUR, OF PARIS, FRANCE, ASSIGNOR TO GENERAL ELEC- TRIC COMPANY, A CORPORATION OF NEW YORK.

DYNAMIC-ELECTRIC MACHINE.

Specification of Letters Patent.

Patented Feb. 5, 1907.

To all whom it may concern.-

Be it known that I. MARIUS O. A. LATQUR, a citizen of the French Republic, residing at Paris, France, have invented certain new and useful Improvements in Dynamo-Electric Machines, of which the followlng is a specification.

My invention relates to dynamo-electric machines, and consists in an improvement in the arrangement described in Patent No. 789,436, issued to me May 9, 1905, which patent shows a novel means for producing a unidirectional flux in a magnetic circuit by means of alternating currents, so as to enable an alternating-current generator to excite its own field-magnet by currents derived from the armature, so that it will be selfeXciting,self-com ounding, or both.

The invention isclosed in my former patent, as well as the present improvement, is based on the mathematical truth expressed by the equation 5 applied this formula by superimposing in a single magnetic circuit a plurality of magnetomotive forces each varying as the sine of the phase angle of one of a plurality of phases, accomplishing this by impressing upon a magnetizing-windmg polyphase voltages and simultaneously varying the eiiectlve number of turns connected to each phase of the voltage in accordance with the variations of the sine of the phase angle of said voltage.

' The description thus far of my former patent applies equally to my present invention.

The improvement consists in the particular arrangement whereby the effective turns of the exciting-winding are varied in the desired manner. For accomplishing this purpose I showed an arrangement in my former patent in which the magnetizlng-windlng was formed of a plurality of sections, the number of turns of the sections varying with a sine function, all the sections being con nected in series in the closed circuit and the oints of connection between the sections eing connected to a many-part commutator. If current is supplied through the commutator to the magnetizing-winding and the commutator is revolved, the eflective'turns of the magnetizing-winding are varied in accordance with the sine function, owing to the proportioning of the number of turns con nected between adjacent segments of the commutator.

By my present invention I am enabled to form the winding of equal sections and obtain the desired variation in effective turns by varying the width of the commutatorsegments. Obviously as far as operation of the machine is concerned it makes no difference whether the segments are all of the same width and the coil-sections varied or the coil-sections are all of the same number of turns and the commutator-segments are of different widths. In either case the rate of the variation in the number of effective turns will vary in different positions of the commutator relative to the brushes.

My present invention accordingly consists in the combination of a magnetic circuit, an

' exciting-winding therefor provided with a many-part commutator, the number of turns in the several windings connected between adjacent segments of the commutator being equal and the widths of the commut ator-segments varying progressively in accordance with a sine function, and means for supplying polyphase voltages to said commutator.

My invention further consists in an application of the above arrangement to the excitation of alternating-current dynamo-electrio machine.

My invention will best .be understood by reference to the accompanying drawings, in which Figure 1 shows, somewhat diagrammatically, an alternating-current dynamo-electric machine provided with a field excitation in accordance with my present invention; and Fig. 2 is an explanatory diagram.

Referring first to Fig. 2, A represents a portion of a magnetic circuit on which is placed a number of sections a to a, one half of the sections being wound oppositely to the other half and the whole connected in a closed circuit. The closed-circuit winding formed by these sections is tapped at points between adjacent sections to the segments of a six-part commutator O. B B represent brushes bearing on the commutator. Evidently the number of effective turns of the winding connected incircuit with the brushes w v du ing-the rota ons brush s- Considerin the number of turns each sec-.

-The number 0! turns in the second cell 5 k sin. n+ The mber a t rn n he t d 11; k-sinfig. i

Z be ng a on t n nd n being t e num ef oi s Now, as has been ointed out above, it mak s a s l tely n .ifi n n th pe ation. of the ma hin whe her h ls vary in number f tu n nd h gm ts a qual or the coils are e ual and the segments vary in width. In either case any desired rate of variation in effective number of turns may be obtained. In other words, the formulae iven above, if the coil-sections are equal, will give the proper width of the commutator-segments or obtaining the desired variation. Rewriting the formulae as applied to the width of commutator-segments, we have the following:

The width of first segment: k sin. a.

The width of the second segment I sin. (147%.

The width of the third segment a sin. (19%, e.

in being a constant and n the number of segments.

'N ow in order to take a simple example let Substituting these values in the expressions given above, the width of the several segmentswill be asfollows: 1, 2,1, 1,, 2, 1. It is this arrangement thatis shown in 2, the negative signs being taken care of by reversing the direction of winding one-half the segments, as shown.

N w f e u h B B are pla ed, a shown, on the commutator it will be seen that the current on entering and leaving the brushes divides, half going through each ha f Of t i n nd the c rr nt n all th sections assisting in producing the n agneti-. zation that is, the total number of ampere-. turns is equal to 31, I bein the current en-. tering at the brushes. If t 's current is an alternating current, the ampere-turns at any instant will be equal to. 31 sin. a, where I is the maximum value of th current enter: ing the brushes, N 0W if the brushes B B ar r d in yn hr nism wi h th al nati n ef th c rrents enter ng the brushe the effective number of turns traversed by the current entering the brushes will also vary, as sin. a, and the resultant ampere- .turi s at an instant may be'expressed by -ampere-turns the'eft'ective value of which atany instant will be equal to 31 cos. a, and i th resultant will be equal to 3Ithat is, the flux will be constant and unidirectionaland in general if an polyphase arrangement of brushes is emp oyed on the commutator C and if pol phase currents are supplied to those brus es of a frequency corresponding to the speed of relative rotation of brushes and commutator a constant unidirectional flux will be produced in the magnetic circuit A, Furthermore, an external polyphase source is not essential for supplying the 01g phase Currents to the commutator. I? t e second set of brushes, as described above, be simply short-circuited instead of being connected to a source of current displaced ninety electrical degrees in phase, a current will flow throu h the short circuit, due to the induction in t e exciting-winding, and the ma netomotive force due to this current wil vary approximately with the square of a sine function, and with the magnetomotive force due to the current impressed upon the first set of brushes will produce a substantially constant unidirectional flux, though this arrangement is not as efficient as an excitation from an external polyphase source. For producing such a flux it is merely essential that the necessary magnetomotive forces, each varying as a sine function, should be produced, and the source of the current which produces them is immaterial.

Now, referring to Fig. 1, the application of my invention to a self-exciting or self-con:- pounding dynamo-electric machine will be explained. in this figure, D represents the armature of a three=phase machine, the armature-terminals being represented at d. E represents the field-spider, carrying the field-coils F and the commutator C, onwhich bear the three brushes B B B, displaced from each other by one hundred and twenty electrical degrees. The winding of each individual field-coil is in six sections, corresponding to the six sections shown in Fig. 2,

one-half of the sections being inversely wound or connected. The first sections of all the field-coils are connected in series with each other in one grou and the group is then connected to a secon group forn ed by the second sections of all the field-coils, the last section of the last group being connected to the first section of the first group. All

the several sections are thus' connected in a closed circuit. The points of connection between one section of the last field-coil of one oup and the following section of the first eld-coil of the next group is connected to a segment of the commutator C. This commutator is provided with eighteen segments in three groups of six se ments eac the corresponding segments of each group being electrically connected. Thus there 1s.

one group per pair of poles, and each group corresponds to the six-part commutator shown in Fig. 2, having two segments of twice the width of the remaining segments. T represents a transformer having its primary,connected to the arm ature-circuit and its secondary connected to the brushes B B machine may be self-exciting or self-compoundin or both, and with very little change om the standard construction of synchronous alternating-current machines.

The improved arrangement, as above described, possesses certain mechanical advantages over the particular arrangement shown in my earlier patent, No. 789,436. In the earlier patent the sectio us were of different numbers of turns, and in order to maintain the resistance of the field-circuit uniform it is desirable that the sections should be of the same resistance in spite of the difference in the number of turns, or, in other words, that the sections with the larger number of turns should be wound with conductors of greater cross-section, as pointed out in my former patent. With the present arrangement the coil-sections can all be equal in both the number of turns and in crosssection and the proper rate of variation secured by adjusting the width of segments. It is of course true that my present invention does not utilize the field-copper to the very best advantage; but the slight difference in efficiency of the field-winding will ordinarily be of negligible importance.

It will of course be understood that when in the foregoing description and appended claims I speak of commutator-segments of different widths I mean of different widths electrically. Whether the commutator is built up of bars which are all insulated from each other and some of the bars have a greater width mechanically than others or whether the commutator is built up of bars all of the same mechanical width and two or more bars electrically connected to form electricallya single segment of the width desired, is of course entire y immaterial for the urposes of my invention. Accordingly do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the a pended claims to cover all modifications w 'ch are within the scope of my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In combination, a magnetic circuit, an exciting-Winding therefor provided with a many-part commutator, the number of turns in the several sections connected between adjacent segments of the commutator being equal and the widthof the commutator-segments varying progressively in accordance with a sine function, and means for supplying polyphase currents to said commutator.

2. In combination, a magnetic circuit, an exciting-winding comprising a plurality of equal coils or sections connected in series in a closed circuit, half of said sections-being reversely wound relatively to the other half, a many-part commutator having its segments connected to the terminals of the severalsections and said segments varying progressively in width in accordance with a sine function, and means for supplying polyphase currents to said commutator.

3. In a dynamo-electric machine, a fieldmagnet, field-coils thereon arranged in equal sections one half of which are reversely Wound relatively to the other half, a manypartcommutator connected to the field-Winding and having segments varying progressively in Width in accordance with a sine function, and means for supplying polyphase currents to said commutator.

4. In a dynamo-electric machine, a fieldmagnet, a winding for each pole thereof com prising a plurality of equal sections, one half of which are reversely wound relatively to the other half, similar sections of all the Windings being connected in a group and all the groups being connected in series in a closed circuit, a many-part commutator connected to the points of connection between the several groups, and having segments varying progressively in width in accordance with a sine function, and means for supplying polyphase currents to said commutator.

5. In a dynamo-electric machine, a polyphase armature-winding, a field-magnet, a winding for each pole of the magnet comprising a plurality of equal sections, one half of which are reversely wound relatively to the other half, similar sections of all the polewindings being connected in a group and all the groups being connected in series in a closed circuit, a many-part commutator connected to the points of connection between IIO ' m nu In witness whereof have hemmeo me my hand this 8th day of November, 1906.

MARIUs 0. A. LAIOUR;

the several groups and havin segments varying progressively in width in accordance with a sine functmn, a. polyphase arrange' ment of brushes bearing on the commutator, 5 and connections for sup' lyin' to said brushes I Witnesses:

polyphase currents derived om the arma-- BENJAMIN B. HULL,

ture. MARGARET E. WGOLLEY. 

